1. Field of the Invention
The present invention relates to an ink jet recording device having a manifold fluidly connecting an ink cartridge with an ink jet head.
2. Description of the Related Art
A conventional ink jet recording device includes an ink jet head having actuators. The actuators are formed from an electromechanical converting element or electrothermal converting element, and define a plurality of ink chambers aligned in a row. An ink cartridge storing ink is detachably attached to the ink jet head by a manifold. The manifold is formed with an ink supply path that normally broadens from the ink cartridge side to the ink jet head side so as to encompass the entire row of ink chambers. Ink in the ink cartridge is supplied through the ink supply path of the manifold into the ink chambers. When the actuators are energized, ink is ejected from the ink chambers through nozzles to form an image on a recording medium.
Normally, ink stored in the ink cartridge has some air dissolved therein. Also, a certain volume of air is introduced into the ink supply path of the manifold when the ink cartridge is exchanged. The air in the ink supply path can grow into a large air bubble, and obstruct supply of ink into the ink chamber. Also, the air can be drawn into the ink chambers along with ink, thereby blocking the ink chambers. This prevents ink from being ejected from the ink chambers, resulting in defective printing.
In order to overcome these problems, purging operations are performed periodically and also directly after the ink cartridge is exchanged. Specifically, a negative purging pressure is applied to the nozzles of the ink jet head. As a result, fresh ink is supplied from the ink cartridge into the ink supply path and the ink chambers. At the same time, air is sucked out of the ink supply path with some ink.
However, when fresh ink is introduced from the ink cartridge, the speed of ink flow greatly reduces at position where the ink supply path broadens. As a result, ink does not easily reach corner portions of the ink supply path, so that the air usually remains at the corner portions. Then, the residual air clings to an inner surface of the ink supply path. When the air floats freely as small air bubbles in the ink supply path, the air bubbles are easily discharged by the purging operations. However, air bubbles that cling to inner surfaces are not sufficiently discharged even during the purging operations. Particularly, the air tends to froth up at locations where the shape of the ink supply path changes. Resultant bubbles cling the side surfaces.
The residual air bubbles which have not been discharged even during purging operations grow into large bubbles, and eventually block the ink chambers. Accordingly, printing will become defective shortly after purging operations. This requires that purging operations be frequently performed during printing. Because purging operations require several minutes to perform, this prevents smooth and quick printing operations.